SU1218079A2 - Arrangement for declaying and mud grouting of well walls - Google Patents

Description

The invention relates to the mining industry, to the field of drilling wells, in particular to the preparation of a well bore for cementing using devolatilization devices and clogging of the borehole walls.

The invention can be used to prepare the wellbore before launching the casing to be subsequently cemented, as well as to clean the bottom-hole formation zone from the filtrate penetrating into it.

The aim of the invention is to improve the efficiency of the device due to the possibility of controlling the clogging process.

FIG. 1 shows a device for scaling and clogging of the walls of the well, a longitudinal section; in fig. 2 shows section A-A in FIG. one.

The device comprises a housing 1 with nozzles 2 located in its upper part, a guide sleeve 3, rigidly connected to the case by means of spacers 4, and a forming ring 5, rigidly connected to the guide sleeve 3, for example, a thread; ring 5 is located above the nozzles 2.

The device works as follows. A device for exaggeration and clogging of the borehole walls is lowered into the Well on the drill pipes through which the flushing fluid is supplied. The flushing fluid leaves the nozzles 2 and creates a local turbulence in the annular space formed by the cylindrical outer wall of the housing 1 and the internal curved surface of rotation of the forming ring 5. The local eddy formation is accompanied by a decrease in pressure in the axial zone of the vortex, which is transmitted to the borehole wall through the annular cavity formed the housing 1 and the inner cylindrical surface of the guide sleeve 3. When the pressure in this cavity reaches a value less than The cluster pressure at this depth, the clay crust due to the pressure difference that has formed, departs from the borehole wall and rushes through the cavity formed by the guide sleeve 3, the forming ring 5 and the housing 1, into the annulus, through which it is carried to the surface.

The jets of nozzles 2 act on the forming ring 5 and depending on the distance between the impact site.

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jets of flushing fluid with a forming ring and its upper edge, and also depending on the law according to which the curvilinear surface of the forming ring is made, have a different clogging effect on the borehole wall.

The clogging effect of the mud streams flowing from the nozzles 2 of the device is due to two effects: blockage of the pores of the rock under the action of the dynamic pressure of the jet and blockage of the pores under the action of the centrifugal force of the vortex formed as a result of eccentrically located nozzles. By changing the height of the forming ring 5, you can fully use the dynamic head (with a ring height of up to 0.2 of its outer diameter) or reduce clogging effect, eliminating the effect of dynamic head (with a ring height of more than 1.8 diameter). The numerical values of these limits are chosen based on the fact that the effect of the interaction of the forming ring with a height of up to 0.2 of its outer diameter with the jet is almost absent, and its shielding effect reaches its maximum value at a height of 1.8 outer diameter and then remains almost constant.

Thus, a ring with a height of 0.2-1.8 times its outer diameter is required to control the degree of clogging.

Control of the degree of glytization is carried out by changing the law of the description of the internal curvilinear surface of the forming ring. The plane in which the axial orifices of the nozzles are located is at the focus of the paraboloid of rotation, which is the inner surface of the forming ring 5. According to the parabolic properties of the mud stream, when interacting with the paraboloid, the rotation rushes up parallel to the axis of the paraboloid, i.e., up the well. In this case, the ejection of the device reaches its maximum value, and to reduce the ejection capacity and to create a jet direction different from the axis of the device, the inner surface of the forming ring can be performed according to other laws, for example, by the hyperboloid of rotation.

Thus, taking into account the properties of rocks, the technical and economic requirements for the borehole wall, it is possible, by changing the length and shape of the forming ring, to control the erosion and collimation capacity of the device.

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Claims (1)

DEVICE FOR LAYOUT AND COLMATATION OF WALLS WELLS by ed. St. No. 1051236, characterized in that, in order to increase the operating efficiency of the device due to the possibility of controlling the process of mudding, it is equipped with a forming ring rigidly connected to the guide sleeve, the upper end of which is installed above the nozzles, and the forming ring has a height of 0.2-1 , 8 of its outer diameter, and its inner surface has a curved shape, determined by a parabolic or hyperbolic law. FIG. 1